Advanced Stirling radioisotope generator

The energy conversion process used by an ASRG is significantly more efficient than previous radioisotope systems, using one quarter of the plutonium-238 to produce the same amount of power.

[10] The higher conversion efficiency of the Stirling cycle compared with that of radioisotope thermoelectric generators (RTGs) used in previous missions (Viking, Pioneer, Voyager, Galileo, Ulysses, Cassini, New Horizons, Mars Science Laboratory, and Mars 2020) would have offered an advantage of a fourfold reduction in PuO2 fuel, at half the mass of an RTG.

[11] The two finished units had these expected specifications:[12] ASRGs could be installed on a wide variety of vehicles, from orbiters, landers and rovers to balloons and planetary boats.

A spacecraft proposed to use this generator was the TiME boat-lander mission to Titan, the largest moon of the planet Saturn, with a launch intended for January 2015,[13][14] or 2023.

It was proposed in 2013 to fly three ASRG units on board the FIRE probe to study Jupiter's moon Io for the New Frontiers program Mission 4.